This invention relates to a PRF adjustment method and apparatus, an ultrasonic wave imaging apparatus, and in particular, to a method and apparatus for adjusting the PRF (pulse repetition frequency) when an image is acquired based on the Doppler shift of an ultrasonic wave echo, and an ultrasonic imaging apparatus comprising a PRF adjustment apparatus.
In ultrasonic wave imaging, a blood flow image or the like is acquired using the Doppler shift of an echo received from a repetitively transmitted ultrasonic wave. The blood flow is displayed as a CFM (Colour Flow Mapping) image showing a two-dimensional distribution of blood flow velocity, a DPDI (Directional Power Doppler Imaging) image showing the presence of the blood flow together with its direction, or a PFD (Pulsatile Flow Detection) image showing a two-dimensional distribution of the pulsation intensity of the blood flow.
To obtain a CFM image, DPDI image or PFD image conveniently, a repetition frequency of a transmitted ultrasonic wave, i.e., a PRF, must be appropriately set, however there was no technique for automating the setting of an optimum PRF, so an operator had to perform the setting by trial and error.
It is an object of this invention to provide a PRF adjustment method and apparatus for obtaining an optimum PRF, and to provide an ultrasonic wave imaging apparatus comprising such a PRF adjustment apparatus.
The invention from a first aspect for resolving the above problem is a PRF adjustment method comprising the steps of calculating the velocity distribution of an echo source based on the Doppler shift of an echo received from a repetitively transmitted ultrasonic wave, calculating the profile of said velocity distribution, correcting the reflection of said profile, detecting the maximum value of the velocity in the corrected profile, and adjusting the repetition frequency of ultrasonic wave transmission based on the maximum value. [0006]
In the invention from this aspect, the PRF is adjusted based on the maximum value of the velocity distribution profile in which reflection is corrected. In this way,the PRF is automatically adjusted according to the maximum velocity.
The invention from another aspect for resolving the above problem is a PRF adjustment apparatus, comprising a velocity distribution calculating means which calculates the velocity distribution of an echo source based on the Doppler shift of an echo received from a repetitively transmitted ultrasonic wave, a profile calculating means which calculates the profile of the velocity distribution, a reflection correcting means which corrects the reflection of the profile, a maximum value detecting means which detects the maximum value of the velocity in the corrected profile, and a repetition frequency adjusting means which adjusts the repetition frequency of the ultrasonic wave based on the maximum value.
In the invention from this aspect, the PRF is adjusted by a reflection frequency adjusting means based on the maximum value of the velocity distribution profile in which the reflection is corrected. In this way, the PRF is automatically adjusted according to the maximum velocity.
The invention from another aspect for resolving the above problem is an ultrasonic wave imaging apparatus, comprising a velocity distribution calculating means which calculates the velocity distribution of an echo source based on the Doppler shift of an echo received from a repetitively transmitted ultrasonic wave, a profile calculating means which calculates the profile of the velocity distribution, a reflection correcting means which corrects the reflection of the profile, a maximum value detecting means which detects the maximum value of the velocity in the corrected profile, a repetition frequency adjusting means which adjusts the repetition frequency of the ultrasonic wave based on the maximum value, and a display means which displays the velocity distribution as an image.
In the invention from this aspect, the PRF is adjusted by the reflection frequency adjusting means based on the maximum value of the velocity distribution profile in which the reflection is corrected. In this way, the PRF is automatically adjusted according to the maximum velocity. A velocity distribution image acquired by this PRF is displayed by the display means. Hence, an appropriate CFM image can be obtained.
The invention from another aspect for resolving the above problem is an ultrasonic wave imaging apparatus, comprising a power distribution calculating means which calculates a power distribution of a Doppler signal based on the Doppler shift of an echo received from a repetitively transmitted ultrasonic wave, a velocity distribution calculating means which calculates the velocity distribution of an echo source based on the Doppler shift of the echo received from the repetitively transmitted ultrasonic wave, a calculating means which calculates the profile of the velocity distribution, a reflection correcting means which corrects the reflection of the profile, a maximum value detecting means which detects the maximum value of the velocity in the corrected profile, a repetition frequency adjusting means which adjusts the repetition frequency of the ultrasonic wave based on the maximum value, and a display means which displays the power distribution as an image.
In the invention from this aspect, the PRF is adjusted by the reflection frequency adjusting means based on the maximum value of the velocity distribution profile in which the reflection is corrected. A power distribution image acquired by this PRF is displayed by the display means. Hence, an appropriate DPDI image can be obtained.
The invention from another aspect for resolving the above problem is an ultrasonic wave imaging apparatus, comprising a pulsation intensity distribution calculating means which calculates a pulsation intensity distribution of an echo source based on the Doppler shift of an echo received from a repetitively transmitted ultrasonic wave, a velocity distribution calculating means which calculates the velocity distribution of the echo source based on the Doppler shift of the echo received from the repetitively transmitted ultrasonic wave, a calculating means which calculates the profile of the velocity distribution, a reflection correcting means which corrects the reflection of the profile, a maximum value detecting means which detects the maximum value of the velocity in the corrected profile, a repetition frequency adjusting means which adjusts the repetition frequency of the ultrasonic wave based on the maximum value, and a display means which displays the pulsation intensity distribution as an image.
In the invention from this aspect, the PRF is adjusted by the reflection frequency adjusting means based on the maximum value of the velocity distribution profile in which the reflection is corrected. In this way, the PRF is automatically adjusted according to the maximum velocity. The pulsation distribution image acquired by this PRF is displayed by the display means. Hence, an appropriate PFD image can be obtained.
The invention from another aspect for resolving the above problem is an ultrasonic wave imaging method comprising the steps of calculating the velocity distribution of an echo source based on the Doppler shift of an echo received from a repetitively transmitted ultrasonic wave, calculating the profile of the velocity distribution, correcting the reflection of the profile, detecting the maximum value of the velocity in the corrected profile, adjusting the repetition frequency of ultrasonic wave transmission based on the maximum value, and displaying the velocity distribution as an image.
In the invention from this aspect, the PRF is adjusted based on the maximum value of the velocity distribution profile in which the reflection is corrected. In this way, the PRF is automatically adjusted according to the maximum velocity. A velocity distribution image acquired by this PRF is displayed. Hence, an appropriate CFM image can be obtained.
The invention from another aspect for resolving the above problem is an ultrasonic wave imaging method, comprising the steps of calculating a power distribution of a Doppler signal based on the Doppler shift of an echo received from a repetitively transmitted ultrasonic wave, calculating the velocity distribution of an echo source based on the Doppler shift of the echo received from the repetitively transmitted ultrasonic wave, calculating the profile of the velocity distribution, correcting the reflection of the profile, detecting the maximum value of the velocity in the corrected profile, adjusting the repetition frequency of the ultrasonic wave based on the maximum value, and displaying the power distribution as an image.
In the invention from this,aspect, the PRF is adjusted based on the maximum value of the velocity distribution profile in which the reflection is corrected. In this way, the PRF is automatically adjusted according to the maximum velocity. A power distribution image acquired by this PRF is displayed. Hence, an appropriate DPDI image can be obtained.
The invention from another aspect for resolving the above problem is an ultrasonic wave imaging method, comprising the steps of calculating a pulsation intensity distribution of an echo source based on the Doppler shift of an echo received from a repetitively transmitted ultrasonic wave, calculating the velocity distribution of the echo source based on the Doppler shift of the echo received from the repetitively transmitted ultrasonic wave, calculating the profile of the velocity distribution, correcting the reflection of the profile, detecting the maximum value of the velocity in the corrected profile, adjusting the repetition frequency of the ultrasonic wave based on the maximum value, and displaying the pulsation intensity distribution as an image.
In the invention from this aspect, the PRF is adjusted based on the maximum value of the velocity distribution profile in which the reflection is corrected. In this way, the PRF is automatically adjusted according to the maximum velocity. The pulsation distribution image acquired by this PRF is displayed. Hence, an appropriate PFD image can be obtained.
According to this invention, a PRF adjustment method and apparatus to obtain an optimum PRF, and ultrasonic wave imaging apparatus comprising such a PRF adjustment apparatus, can be realized.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.